Depth camera parameters

[jchevrie]

The file gazebo_cer_depthCamera.ini seems to contain some misleading data.

• the name is set to /${gazeboYarpPluginsRobotName} so that the ports associated to the RGBD camera have misleading names like /SIM_CER_ROBOT/rpc:i.
  It should probably be changed to /${gazeboYarpPluginsRobotName}/depthCamera to have clearly identified port names.

• the whole group of parameters in [CAMERA_PARAM]does not seem to be loaded by the gazebo_depthCamera plugin (camera parameters can only be changed in the cer.sdf file).
  Are these parameters used by anything else (if not, it would probably be better to remove them)?

[valegagge]

About the first point I fixed it in #15